An obvious form of Wish Fulfillment fantasy, this trope allows the protagonist (who is almost always a self-insert or Audience Surrogate, and thus almost Always Male) to enjoy the privilege of a number of servants who are also deeply in love with him/her. The exact nature of the servitude can vary, whether it be legal ownership, Indentured Servitude, a Magically Binding Contract, a pledge of eternal fealty, Mind Manipulation, programming or some other form of Unequal Pairing that makes one person forced or obligated to obey the other.
Due to slavery being seen as an unforgivable violation of a person's consent, agency and freedom and sex with a slave being legally a form of rape, this trope is one that many writers shy away from. However, the trope has exploded in popularity within Light Novels, becoming one of the most common forms of Love Interest for the Stock Light-Novel Hero alongside the Shana Clone and Little Sister Heroine (and these are not mutually-exclusive).
Usually, the relationship will be portrayed as "unproblematic", whereas the slaves are content with being owned by their beloved master and may even possess small amounts of "authority" (i.e., the owner may claim that they can be released any time they like or are allowed to speak their mind and maybe even question their orders). They may even avoid the words "slave" or "slavery" altogether, and portray the arrangement as simply "employment" or "working off a debt". In many portrayals, the owner will also be a Chaste Hero who refuses to use their servants as Sex Slaves, regardless of how much they want them to. However, none of this changes the fact that the protagonist has the option to do indecent things with their harem, and the only thing stopping them is their own self-restraint. In this trope, said self-restraint and desire not to abuse their power is often portrayed as the virtuous, heroic thing to do in opposition to simply freeing the slaves outright.
To be clear, this trope carries a ton of Unfortunate Implications, not helped by the fact that enslavement is historically one of the most cruel things that one person can do to another, and has been outlawed in many countries with good reason. In Japanese Media, this trope also carries high levels of Values Dissonance; in the West, subservience is typically portrayed as a weakness or gross injustice, but in the East, it is often seen as a sign of purity, selflessness and devotion. It is also often portrayed closely to BDSM.note
A Sub-Trope of Property of Love. Also a form of Romanticized Abuse and Protagonist-Centered Morality, as the trope is usually provided justification under the logic that there's no problem if the protagonist is a Nice Guy and treats his servants well. Compare Royal Harem, when the person with the harem is a ruler or sovereign.
Contrast Exotic Extended Marriage (when a foreigner is the one with a harem to add a degree "otherness").
- Death March to the Parallel World Rhapsody: Satou saves a trio of demihuman slaves from an abusive master, and they choose to stay with him. Later, he is Glamoured into buying a pair of sisters as slaves because one of the sisters is highly attracted to him and was hoping he'd use her as a Sex Slave. Even later still, he saves nine gynoids who also pledge themselves to his service (one of whom repeatedly tries to sleep with him). Satou, however, Has a Type and Likes Older Women, meaning that almost of his slaves (whose ages range from very young to mid-teens) are too young for him. Later in the story, however, they manage to trick him into saying he will marry them if they're available in ten years or more.
- How NOT to Summon a Demon Lord: When the protagonist Diablo is summoned to a fantasy world, his ring that deflects all magic reverses the slave spell that the two girls who summoned him had used and thus makes them his slave instead of the other way around. At first, no one is happy with the arrangement and look for ways of reversing the spell, but after Diablo shows himself to be a Nice Guy underneath his Jerkass Façade, the girls fall in love with him. He acquires more girls later (some, though not all, being slaves as well).
- Hyakka Ryouran Samurai Girls: Defied trope via Insistent Terminology. The Central Theme of the series is that the heroes argue that the relationship between samurai and their general is not slavery — that even if a samurai is sworn to protect and obey their general, this comes from a place of mutual respect, trust and bonding rather than servitude. The villains, however, are particularly those who see no difference, and use samurai as disposable tools, fodder and even sex slaves. However, this debate coincides with the fact that the master samurai introduced are all women and most serve the protagonist, Muneakira Yagyu.
- In Another World with My Smartphone: In addition to the main heroines that act as his brides, protagonist Touya Mochizuki also eventually acquires nine artificial human gynoids which were specifically created to be sex bots for him. After imprinting him as their master, all nine robots want nothing more than to be "used" by Touya, with Cesca in particular being extremely aggressive about it. On top of this, Touya eventually becomes king of his own country and many women under his command also show an interest in being a mistress or otherwise having a romantic relationship with him.
- Lord Marksman and Vanadis: Double Subverted in regards to Tigre and Elen; early in the story, she takes him prisoner after he fails to defeat her in battle, intending to use him as a ransom. As a prisoner, the two of them become more interested and attracted to one-another, although Elen always reminds Tigre (as well as any other girls desiring him) that he "belongs" to her. Later in the story, however, Tigre gains more and more political power to the degree that several groups and nations swear fealty to him, including Titta, his personal servant since childhood.
- The Master of Ragnarok & Blesser of Einherjar: Yuuto Suoh is summoned to another world/time and made the Patriarch of the Wolf Clan after the original Patriarch dies. As such, the members of the clan (as well as those of other clans whom the Wolf Clan conquers) take a "Chalice Oath" in which they swear fealty to him and claim to be his property. Many of these women also begin to call themselves his "daughters" or "little sisters", but nonetheless want to become his wife or one of his mistresses.
- Monster Girl Doctor: Discussed Trope between Kay, Lorna and Dr. Glenn. Kay and Lorna are the sword servants of lady Tisalia, and describe themselves as their lady's "property" under centaur tradition. When alone with Glenn, the two of them try to seduce him, knowing that their mistress is in love with him, under the logic that if successful, Glenn would have no choice but to marry Tisalia in order to take responsibility. When their attempt fails, the two are unfazed and state that they only see it as a matter of time before Glenn marries Tisalia, and since centaur law dictates that spouses share all property, then that will make them his property as well...which they are very excited about.
- Overlord (2012): Ainz Ooal Gown is the supreme ruler of The Great Tomb of Nazarick, and because every resident besides himself were once videogame NPCs, they are bound to obey his will. Several female NPCs in the Tomb are also either in love with him (Albedo, Shalltear) or greatly lust after him (Solution Epsilon and Neuronist Painkill). While Ainz is a Villain Protagonist, he is A Lighter Shade of Black who is both aware of the interests of his female subjects and in fact disturbed by it. He confesses to Albedo at one point that he reset her settings to be in love with him, but she dismisses it and says that if her love doesn't bother him, then she sees no problem.
- Redo of Healer: The protagonist Keyaru gains healing abilities in his adolescence but quickly finds out that they come with horrific drawbacks. The sadistic Princess Flare thus takes him prisoner, makes him addicted to drugs, and has him repeatedly raped by several members of both genders (due to sex making others' abilities stronger). After he eventually becomes immune to drugs, he rewinds time to the beginning and starts acquiring new abilties, eventually learning how to erase memories and other forms of Mind Manipulation. Afterwards, Flare becomes "Freya", a much kinder and nicer person who falls deeply in love with Keyaru. Later, he also purchases a beast girl named Setsuna, who also becomes fiercely devoted to him. He later also brainwashes Flare's younger sister Norn (who is even worse than Flare), and she becomes "Ellen", who also eagerly has sex with Keyaru.
- The Rising of the Shield Hero: Early into the story, the hero Naofumi purchases a beast child named Raphtalia to be his combat slave. In the original novel, he intentionally did this for the purpose of seeing a woman get hurt, as a form of revenge-by-proxy against Myne (who ruined his life with a False Rape Accusation). However, after being cured of an illness, being well taken care of, and taught to become a stronger person, Raphtalia quickly falls in love with Naofumi and happily continues to be his slave. He also later gains several other slaves as well, some of whom also fall in love with him.
- The Testament of Sister New Devil: The protagonist Basara establishes a master-servant contract with several women, with erotic and sexual contact explicitly essential to it. The contract prevents a servant from acting or even thinking of disobeying their master's wishes, as it will immediately make them Overcome with Desire to a crippling degree and can only be freed from such desire by their master. It's also demonstrated that other conditions can be met to "punish" slaves, such as teleporting them to another dimension. To highlight just how easily-abusable this system is, the Big Bad Zolgia and several of his followers/admirers take joy in using the contract to make women their Sex Slaves, and especially taking other men's slaves and using the agony and discomfort of the contract to break their minds until they enter a vegetative state and can be sexually abused at will.
- The Tough Guide to Fantasyland: When it talks about "Slaves, Female" of the Royal Harem type:
"Beautiful young women. You will find these in droves in the FANATIC CALIPHATES and sometimes in the PALACES of bad KINGS. Their duties are light and pleasant and are: looking beautiful, bathing and massaging visitors, singing and dancing, and, for male Tourists, providing company in bed. None of them seem unhappy in their work and they show no desire to escape. [...] Often male Tourists will sympathize with the plight of such Slaves, nobly reject their offer of free, no-holds-barred SEX, insist on assisting them to escape from the exploitative tyranny under which they have been existing, and then, having obviously done them a Good Turn, have free, no-holds-barred Sex before stranding them in the middle of nowhere to make their way thousands of miles back to their own COUNTRY."
- Drakengard 3: This trope gradually manifests in the form of Zero and her male Battle Harem, consisting of Dito, Decadus, Octa, and Cent. Prior to the main events of the game, the latter group existed to serve as bodyguards and concubines for the Intoners, a group of six goddesses with the power of Magic Music of which Zero is the eldest. As Zero kills her sisters in her plan to become the only living Intoner in existence, she recruits each sister's respective Disciple, all of whom who pledge their loyalty to her.
- Discussed Trope (although without the "harem" aspect) in Explanation Point's analysis of The Rising of the Shield Hero. He argues that the reason slavery has become so popular and enjoyable for many fans of isekai/light novel power fantasies is for two reasons. One, slaves are "blameless" and are thus free of the same flaws and evil that plagues the rest of humanity. And two, the trope presents a world in which the capitalist ideal works, whereas serving a "great" person also benefits the person doing the serving. However, he also notes that this only works because Naofumi himself is unrealistic; Naofumi never treats his slaves with contempt and never tries to take more than what he needs from them or others he has power over, which (he argues) is the case more often than not in Real Life.
"Raphtalia is capable of providing Naofumi with all the benefits of human companionship without any of what Naofumi would consider to be the 'pitfalls' of humanity. She's incapable of betrayal, deceit, lies. Why? Exactly because she's a slave, forced by magic to be perfectly subservient. This is Shield Hero's idea of the responsibility of the powerless to the powerful. They're intended to be tools, assisting those with power and influence in achieving their goal. [...] This hits on the capitalist ideal that Shield Hero's world is trying to present: that which benefits Naofumi benefits Raphtalia because Raphtalia serves Naofumi. In serving Naofumi, Raphtalia is, in turn, serving herself. Likewise, in serving himself, Naofumi is serving Raphtalia, and (inadvertently or not) he serves society at large. As I said before, Shield Hero argues that what's good for the individual is, ultimately, good for the collective, whether they intend it to be or not."
- Discussed Trope in the Terrible Writing Advice "Isekai" episode, when he discusses harems. He breaks character in shock when he reads that this is a popular trope in his script, and then lampshades the creepiness of the protagonist supporting slavery instead of heroically ending it.